Quantification of the influence of drugs on zebrafish larvae swimming kinematics and energetics

The use of zebrafish larvae has aroused wide interest in the medical field for its potential role in the development of new therapies. The larvae grow extremely quickly and the embryos are nearly transparent which allows easy examination of its internal structures using fluorescent imaging techniques. Medical treatment of zebrafish larvae can directly influence its swimming behaviours. These behaviour changes are related to functional changes of central nervous system and transformations of the zebrafish body such as muscle mechanical power and force variation, which cannot be measured directly by pure experiment observation. To quantify the influence of drugs on zebrafish larvae swimming behaviours and energetics, we have developed a novel methodology to exploit intravital changes based on observed zebrafish locomotion. Specifically, by using an in-house MATLAB code to process the recorded live zebrafish swimming video, the kinematic locomotion equation of a 3D zebrafish larvae was obtained, and a customised Computational Fluid Dynamics tool was used to solve the fluid flow around the fish model which was geometrically the same as experimentally tested zebrafish. The developed methodology was firstly verified against experiment, and further applied to quantify the fish internal body force, torque and power consumption associated with a group of normal zebrafish larvae vs. those immersed in acetic acid and two neuroactive drugs. As indicated by our results, zebrafish larvae immersed in 0.01% acetic acid display approximately 30% higher hydrodynamic power and 10% higher cost of transport than control group. In addition, 500 μM diphenylhydantoin significantly decreases the locomotion activity for approximately 50% lower hydrodynamic power, whereas 100 mg/L yohimbine has not caused any significant influences on 5 dpf zebrafish larvae locomotion. The approach has potential to evaluate the influence of drugs on the aquatic animal’s behaviour changes and thus support the development of new analgesic and neuroactive drugs

A study of zebrafish locomotion using experimental and numerical simulation

Zebrafish larvae has aroused worldwide attention in the medical field for assisting the development of new medicines because of its biological nature. To study the interactions between swimming zebrafish and surrounding fluid, we have developed a novel tool to exploit intravital changes based on the experimentally observed zebrafish locomotion. By using our in-house MATLAB code and a customized Computational Fluid Dynamics (CFD) tool, we are able to simulate the real zebrafish swimming which is comparable to the observed live zebrafish

Transcriptome profile of halofuginone resistant and sensitive strains of Eimeria tenella

The antiparasitic drug halofuginone is important for controlling apicomplexan parasites. However, the occurrence of halofuginone resistance is a major obstacle for it to the treatment of apicomplexan parasites. Current studies have identified the molecular marker and drug resistance mechanisms of halofuginone in Plasmodium falciparum. In this study, we tried to use transcriptomic data to explore resistance mechanisms of halofuginone in apicomplexan parasites of the genus Eimeria (Apicomplexa: Eimeriidae). After halofuginone treatment of E. tenella parasites, transcriptome analysis was performed using samples derived from both resistant and sensitive strains. In the sensitive group, DEGs associated with enzymes were significantly downregulated, whereas the DNA damaging process was upregulated after halofuginone treatment, revealing the mechanism of halofuginone-induced parasite death. In addition, 1,325 differentially expressed genes (DEGs) were detected between halofuginone resistant and sensitive strains, and the DEGs related to translation were significantly downregulated after halofuginone induction. Overall, our results provide a gene expression profile for further studies on the mechanism of halofuginone resistance in E. tenella

Comparative Transcriptome Analysis Reveals Genes Associated with the Gossypol Synthesis and Gland Morphogenesis in Gossypium hirsutum

Gossypium hirsutum is an important source of natural textile fibers. Gossypol, which is a sesquiterpenoid compound mainly existing in the cotton pigment glands, can facilitate resistance to the stress from diseases and pests. The level of gossypol in the cotton is positively correlated to the quantity of pigment glands. However, the underlying regulatory mechanisms of gossypol synthesis and gland morphogenesis are still poorly understood, especially from a transcriptional perspective. The transcripts of young leaves and ovules at 30 DPA of the glanded plants and glandless plants were studied by RNA-Seq and 865 million clean reads were obtained. A total of 34,426 differentially expressed genes (DEGs) were identified through comparative transcriptome analysis. Genes related to gossypol synthesis or gland morphogenesis displayed significant differential expression between the two cultivars. Functional annotation revealed that the candidate genes related to catalytic activity, the biosynthesis of secondary metabolites, and biomolecular decomposition processes. Our work herein unveiled several potential candidate genes related to gossypol synthesis or gland morphogenesis and may provide useful clues for a breeding program of cotton cultivars with low cottonseed gossypol contents

Using Count Data Models to Predict Epiphytic Bryophyte Recruitment in Schima superba Gardn. et Champ. Plantations in Urban Forests

Epiphytic bryophytes are known to perform essential ecosystem functions, but their sensitivity to environmental quality and change makes their survival and development vulnerable to global changes, especially habitat loss in urban environments. Fortunately, extensive urban tree planting programs worldwide have had a positive effect on the colonization and development of epiphytic bryophytes. However, how epiphytic bryophytes occur and grow on planted trees remain poorly known, especially in urban environments. In the present study, we surveyed the distribution of epiphytic bryophytes on tree trunks in a Schima superba Gardn. et Champ. urban plantation and then developed count data models, including tree characteristics, stand characteristics, human disturbance, terrain factors, and microclimate to predict the drivers on epiphytic bryophyte recruitment. Different counting models (Poisson, Negative binomial, Zero-inflated Poisson, Zero-inflated negative binomial, Hurdle-Poisson, Hurdle-negative binomial) were compared for a data analysis to account for the zero-inflated data structure. Our results show that (i) the shaded side and base of tree trunks were the preferred locations for bryophytes to colonize in urban plantations, (ii) both hurdle models performed well in modeling epiphytic bryophyte recruitment, and (iii) both hurdle models showed that the tree height, diameter at breast height (DBH), leaf area index (LAI), and altitude (ALT) promoted the occurrence of epiphytic bryophytes, but the height under branch and interference intensity of human activities opposed the occurrence of epiphytic bryophytes. Specifically, DBH and LAI had positive effects on the species richness recruitment count; similarly, DBH and ALT had positive effects on the abundance recruitment count, but slope had a negative effect. To promote the occurrence and growth of epiphytic bryophytes in urban tree planting programs, we suggest that managers regulate suitable habitats by cultivating and protecting large trees, promoting canopy closure, and controlling human disturbance

Exogenous melatonin orchestrates multiple defense responses against Botrytis cinerea in tomato leaves

Infection of tomato leaves and fruits by necrotrophic fungal pathogen Botrytis cinerea causes considerable economic loss. Melatonin has multiple physiological functions and is considered a potential biocontrol agent for its positive effects on plant innate immunity. In tomato, melatonin reduces Botrytis-caused post-harvest fruit decay by activating jasmonic acid (JA) signaling. In this study, we analyzed the effects of melatonin on resistance to Botrytis and associated defense mechanisms in tomato leaves. Treatment of detached tomato leaves with melatonin at a concentration as low as 100 µM induced resistance to Botrytis based on reduced lesion size and fungal growth. Melatonin-induced resistance to gray mold was associated with activation of a complex set of defense mechanisms in tomato leaves. First, melatonin suppressed Botrytis-induced cell death and accumulation of reactive oxygen species (ROS), which was correlated with increased activities of ROS-scavenging enzymes and enhanced expression of their corresponding genes. Second, melatonin treatment induced callose synthase genes and promoted rapid and strong callose deposition in tomato leaves. Melatonin also induced other anti-microbial genes encoding chitinases, β-1,3-glucanases, phenylalanine ammonialyases and polyphenol oxidases. Third, melatonin increased Botrytis-induced expression of genes encoding SlWRKY33, SlMYC2 and SlERF transcription factors, which activate defense-related genes expression through JA and ethylene (ET) signaling pathways. By contrast, melatonin suppressed salicylic acid (SA) signaling based on reduced expression of the SlPR1 marker gene, which is known to antagonize defense against Botrytis. These results collectively indicate that exogenous melatonin orchestrates multiple signaling pathways to activate a complex set of defense mechanisms against Botrytis in tomato leaves